As an immunosuppressant known heretofore, ciclosporin can be mentioned. Ciclosporin has been used for suppression of rejection in transplantation of the kidney and possesses an excellent immunosuppressive effect.
Ciclosporin, however, has a drawback that it causes side effects (e.g. renal disturbances, hepatic disturbances).
Therefore, there has been demanded immunosuppressants which have potent immunosuppressive activities and the lowest possible side effects.
From such a viewpoint, the present inventors have conducted extensive studies to find that the compounds of the formula (I) mentioned below which include novel compound and their lactone possessed excellent immunosuppressive activities while having lower side effects, and further studies have led to the completion of the present invention.
That is, this invention relates to immunosuppressive agents which comprise at least one compound selected from the compounds of formula ##STR3## wherein R represents a hydrogen atom or an acyl, Y represents carbonyl or hydroxymethylene and bond represents a single bond or a double bond [hereinafter referred to as compounds (I)] and their lactones, in an effective amount and a pharmaceutically acceptable carrier, to a method for suppressing rejection or a method of prophylaxis and therapy for autoimmune diseases which comprises administering at least one compound selected from compounds (I) and their lactones in an effective amount, and to a compound of the formula (I-1) ##STR4## and its lactone.
Referring to R in the present specification, mention is made of, for example, alkanoyls having 2 to 5 carbon atoms such as acetyl, propionyl, butyryl, pivaloyl, etc. and aromatic acyls having 7 to 11 carbon atoms such as benzoyl, phenylacetyl, etc as the acyl.
Preferred compounds (I) and their lactones are as shown below: ##STR5##
Among the above-mentioned compounds, the last two compounds, namely, the compound of the formula (I-1) and its lactone are novel compounds.
The compound of the formula (I) wherein R is a hydrogen atom, is a double bond and Y is carbonyl which is the compound obtained in accordance with Example 1 mentioned hereafter, namely, ISP-I is known as Myriocin or Thermozymocidin [See The Journal of Antibiotics, vol. XXV No. 2, 109-115 (1972), The Journal of Organic Chemistry, 38(7), 1253-1260 (1973), J. Chem. Soc. Perkin Trans. I, 1613-1619 (1983), J. Chem. Soc., Chem. Commun., 488-490 (1982) etc.], with its action being an antifungal action.
Compounds (I) and their lactones can be produced by fermentation method or synthesis method in accordance with, for example, the following Production Methods 1-5.
The production method for ISP-I has been disclosed in the above literatures as well.